1. Field of the Invention
The present invention relates generally to an apparatus for distributing liquid and semi-solid materials from a hopper through the open mouth thereof. More particularly, it relates to such apparatus in which sludge or similar material is deposited, and then uniformly distributed onto an endless filter medium.
2. Related Art
Sludge feed distribution hoppers are well known in the waste treatment industry. Typically, sludge is pumped through a pipe into a hopper, which is in alignment with the upper flight of an endless filter belt. The sludge flows from the mouth of the hopper, i.e., through one open end thereof, and is distributed across the width of the filter belt, hopefully in a fairly even manner.. However, because the sludge, itself, lacks uniformity, it is unlikely that distribution of the sludge within the hopper, and then from the hopper onto the filter belt, will be uniform.
Such lack of uniformity is a problem in the art. When sludge is deposited unevenly on a filter belt, dewatering of the sludge will be inconsistent: where the sludge is thickest, dewatering will be incomplete; where it is thinnest, dewatering ability will be wasted. It will be apparent that for any particular sludge and specific filter belt, maximum dewatering efficiency will depend on a predetermined thickness of the sludge. As a consequence, any deviation from the deposit of a uniform cake of sludge on a filter belt where the thickness of the cake varies from the predetermined optimum, will be derogatory to the dewatering process.
It will be apparent that in order to achieve deposit of a uniform filter cake on the filter belt, the sludge must issue from the mouth of the hopper in a uniform manner In order for this occurrence to take place, there must be a uniform build up of sludge within the hopper although, of course, it is not necessary, or even achieveable, that all of the sludge within the hopper will be at a uniform depth or distribution.
One problem that has been associated with the uniform distribution of sludge within the hopper is the presence of materials that differ substantially from the body of the sludge, e.g., rags or other fibrous materials may be present. Where such bulky materials are present, they may be caught somewhere within the body of the hopper, and sludge will tend to build-up behind and about the fibrous materials. After several hours of operation, this build-up can be quite substantial and reach a Point where the filter system will have to be shut down and cleaned. At the least, the presence of fibrous material in a sludge distribution hopper requires frequent operator attention.